The long range goal of our research is the correlation of gene expression profiles with the phenotype of a plant. For that purpose it is necessary to evaluate the expression of many genes in parallel and construct a physiological model of a cell, tissue and the whole organism. At present, global expression analyses are possible at the mRNA level by using cDNA arrays, whereas analyses of similar complexity at the protein or metabolite level are much more difficult. cDNA arrays are membranes or other types of solid support onto which gene fragments of many different genes are spotted with a defined order. Those arrays can then be used for hybridization experiments with labeled cDNA prepared from different tissues or physiological situations. The intensity of a hybridization signal at a certain gene fragment correlates with the amount of mRNA for that gene within the used cDNA. Determination of all signals on the cDNA array will yield the mRNA level of every represented gene.
To establish the method, test its potency and evaluate physiological interpretations, we chose a model system, which has been studied extensively before. For that reason we analyse photomorphogenesis and greening of etiolated seedlings - processes which are induced by red and blue light. We do this in the model plant Arabidopsis thalina, because in this system a large number of partialy sequenced cDNA clones (ESTs, expressed sequence tags) are available as well as highly characterized mutants of red and blue light receptors and signal transduction components. With the help of all these tools we try to analyse the interaction of red and blue light signal transduction pathways.

In addition, we are cloning and analyzing cDNA fragments from barley in collaboration with other groups at the IPK, to allow global expression analyses also for crop plants, especially barley. Furthermore, we try to use spotting technology, established for the production of cDNA arrays, for other purposes, e.g. screening and fingerprinting of large ordered libraries and develop these uses together with other groups at the institute. To fullfil all those tasks we have access to modern robot equipment for automated picking of colonies, preparation of plasmids and spotting of cDNA arrays within the framework of the PGRC (Plant Genome Resources Centre) of the IPK.